n. A build up of organic material on the ceiling of an underground subway composed mostly of run off from broken or corroded sewer carrying pipes. It's generally black, white, or brown in color with spotting of one or more of the other colors. It resembles a underwater volcanic plume of carbonic material hanging in cave-like stalactite formations. Often beneath subway stalactite there is also subway stalagmite, with different properties than the supplementary subway stalactite.

Subway Stalactite may be a black, brown or white deposit of sewage or run-off forming plume-like organic spikes.